1. Field of the Invention
The invention relates generally to the field of photography, and in particular to sensor apparatus intended to be used with a film cassette having a built-in support for an optical sensor to read film information.
2. The Cross-Referenced Applications
The cross-referenced applications each disclose a film cassette capable of advancing a filmstrip automatically out of a light-tight cassette shell whether the filmstrip is unexposed, only partly exposed, or substantially exposed. The film cassette is characterized in that a film exposure status indicator can be disposed in any one of three unique exposure-related positions comprising an unexposed position for providing a visible indication that the filmstrip is unexposed, a partly exposed position for providing a visible indication that the filmstrip is only partly exposed, and a fully exposed position for providing a visible indication that the filmstrip is substantially exposed.
More particularly in cross-referenced application Ser. No. 07/560,921, the status indicator and a bar code consisting essentially of a series of optically readable photoreflective and non-reflective bits are coaxially fixed to a film spool rotatable inside the cassette shell to advance the filmstrip out of the shell. The bar code, when read, can be used to stop rotation of the film spool with the status indicator in its partly exposed and fully exposed positions.
In cross-referenced application Ser. No. 07/562,501, the film cassette includes sensor positioning means fixed to the cassette shell for supporting a photoreflective type optoelectronic sensor a suitable distance from the optically readable bits to establish a substantially optimal angle of reflection for the optoelectronic sensor to read the bar code.